An image forming apparatus having a main body to which a process unit is detachably attached is known in general. The process unit includes a developer cartridge accommodating a toner and having a developing roller, and a drum cartridge, to which the developer cartridge is detachably attached, provided with a photosensitive drum.
In such an image forming apparatus, it is known that the developer cartridge attached to the drum cartridge is pressed against the photosensitive drum during image formation, in order to bring the developing roller into contact with the photosensitive drum.
For example, the following image forming apparatus is proposed (refer to Japanese Unexamined Patent Publication No. 2003-84647, for example): A pair of first inclined guide portions are provided on the right and left sides inside a main body case, and a pair of second inclined guide portions arranged therebetween guide the bottom surface of a drum cartridge. When the center axis of the rotation of a photosensitive drum reaches insertion end positions of the first inclined guide portions, the rear portion of the drum cartridge is pivoted downward, so that the drum cartridge is received in a receiving section. Front and rear holders and an urging spring provided in the receiving section sandwich lateral engaging portions protruding from the right and left sides of a developer cartridge, to elastically urge and fix the same.
In another image forming apparatus, it is known that a developer cartridge is provided with a memory which stores information related to the specification and the hysteresis of the developer cartridge, so that a CPU provided in the main body of the image forming apparatus can read the information stored in the memory when the developer cartridge is attached to the main body, to execute image formation corresponding to the developer cartridge.
For example, the following image forming apparatus is proposed (refer to Japanese Unexamined Patent Publication No. 2001-215862, for example): A plurality of cartridges having developer units accommodating developing agents of different colors respectively are attachable to/detachable from this image forming apparatus, in order to develop latent images formed on image carriers. The cartridges are provided with memory units respectively. When an image is monochromatically formed with one of the cartridges, the memory units of the remaining cartridges store information about the monochromatic image formation.
When the developer cartridge is pressed against the photosensitive drum in the aforementioned image forming apparatus, the pressing force of the developing roller to the photosensitive drum must be uniformized, in order to excellently develop a latent image provided on the photosensitive drum.
In order to read the information stored in the memory provided on the developer cartridge with the CPU in the main body, on the other hand, terminals provided on the memory and CPU respectively must be pressed against each other to reliably come into contact with each other, when the developer cartridge is attached to the main body of the image forming apparatus.
If the pressing force for bringing the terminals into contact with each other influences the pressing force of the developing roller to the photosensitive drum, however, the pressing force of the developing roller to the photosensitive drum may be destabilized, so that the latent images may not be excellently developed.